Our aim is to compare the estimates of hepatic blood flow and functional hepatocyte mass using Tc-99m-neogalactoalbumin (Tc-NGA) to standard diagnostic modalities currently employed and to evaluate the prognostic usefulness in various hepatocellular disease states. Tc-99m-NGA enables one to obtain anatomic images as well as information on blood flow and functional hepatocyte mass. In the first year, images obtained with Tc-99m-NGA will be compared to CT, ultrasound, liver biopsy results, and radionuclide images obtained with Tc-99m sulfur colloid and Tc-99m disofenin. Estimates of liver blood flow using Tc-99m-NGA will be compared to simultaneous indocyanine green and galactose clearance blood flow determinations. Functional hepatocyte mass estimates obtained using Tc-99m-NGA will be compared to measurements of functional mass obtained by aminopyrine breath test (ABT) clearance studies. In addition to these modalities, biochemical and physiological data obtained during routine clinical evaluations will be compared to the results obtained with Tc-99m-NGA. In the second year, serial studies using Tc-NGA and ABT will be obtained with a limited number of patients in selected categories of hepatocellular disease. Tc-NGA functional imaging may provide a reliable estimate of quantitative change in hepatocellular function as well as provide an indicator of prognosis.